Variable-delivery pump with stationary cylinders



Feb. 7, 1967 s. REIS 3,302,576

VARIABLE-DELIVERY PUMP WITH STATIONARY CYLINDERS Filed March 24, 1965 INVENTOR: Smn' Refs Attorney United States Patent 3,302,576 VARIABLE-DELIVERY PUMP WITH STATIONARY CYLINDERS Smil Reis, Viale Campania 29, Milan, Italy Filed Mar. 24, 1965, Ser. No. 442,416 Claims priority, application Italy, Mar. 27, 1964, 6,770/ 64 7 Claims. (Cl. 103-37) This invention is referred to a pump of the piston type, with stationary cylinders, which displaces an amount of fluid per working cycle, which can be changed by changing the timing of its suction and exhaust in respect to the constant piston strokes.

Pumps of the above defined kind, with stationary cylinders, have a cam shaft with a cam for displacing the piston along its stroke, and means connected to the same cam shaft for operating the opening and closing of the suction and the exhaust. For changing the timing of said suction and exhaust in respect to the piston stroke, said means are angularly adjustable in respect to the piston operating cam, and to this end, complex mechanical structures are necessary, in order to allow said means, which are turning with the cam shaft, to be angularly adjusted through means stationary and accessible from outside of said shaft.

This invention is aimed to suppress any means for timing the suction and the exhaust of the pump, which are turning with the cam shaft, and are to be adjusted angularly on said shaft for changing the amount of fluid delivered by the pump. By this, also any complex structures for operating the adjustment of the pump timing, will also be suppressed, and the only alternating parts of the pump will be its piston, while its only turning parts will be the cam shaft.

The pump, according to this invention, comprises, at least one cylinder, a piston in said cylinder, a cam and a shaft solid with said cam, for displacing said piston along its stroke, a spring reacting between said cylinder and said piston, for keeping said piston in contact with said cam, a rotating distributor fixed to said cam shaft for opening and closing suitably the suction and the exhaust respectively into, and from said cylinder, a rotative barrel and ports in said rotative barrel for said suction and exhaust, said distributor turning in said rotative barrel, said rotative barrel being angularly adjustable in respect to said piston stroke for changing the timing of said suction and exhaust in respect to said piston stroke, thus changing the pump delivery.

A more detailed description of this invention, is given hereinafter with reference to the annexed drawing, wherein:

FIG. 1 shows schematically in a cross-section of a single cylinder pump, its essential parts, according to the invention;

FIG. 2 shows schematically in a longitudinal section of the pump shown in FIG. 1, its essential parts;

FIG. 3 shows diagrammatically how the pump works;

FIG.4 shows schematically a distributor for a pump with a cam having two lifts per turn of the cam shaft.

With reference to FIGS. 1 and 2, the pump according to the invention, comprises mainly, a stationary cylinder 1, a piston 2 in said stationary cylinder 1, a cam shaft 3 solid with a cam 4, for displacing said piston 2 in said cylinder 1, a spring between the cylinder 1 and a washer 6 of said piston 2, for keeping said piston 2 in contact with said cam 4, a rotative barrel 8 and a distributor therein, said distributor comprising a diametrally parting plane 7 fixed to said cam shaft 3, two semicircular transversally opposed end plates 11, 12, fixed respectively to the ends of said parting plane 7, two opposite distributor chamice bers 9, '10, in said rotative barrel 8, respectively on each side of said parting plane 7 so that said distributor chambers 9 and 10 are open respectively, one towards one, and the other towards the other end of said parting plane 7.

The rotative barrel 8 has a groove 18 extending along a suitable portion of its outer circumference, a port 19 between said groove 18 and the inside of said rotative barrel 8, said groove 18 being located between said opposite semi-circular end plates 11, 12 of said distributor. The rotative barrel 8 has further two outer circumferential grooves 22, 23, one at each side and outside the full length of said distributor, and ports 24, 25 respectively between each of said grooves 22, 23 and the inside of the barrel 8.

The rotative barrel 8 is fitted closely within a stationary barrel 13 having ports 26 and 27 in constant communication respectively with said further grooves 22, 23 of said rotative barrel 8, for admitting and exhausting the pumped fluid to and from the inside of said rotative bar rel 8, and a port 20, for taking from, or sending to said cylinder 1 said pumped fluid.

The cylinder 1, bearings 14, 15, for the cam shaft 3, and said stationary barrel 13 are all suitably fixed to a cam shaft case 31. The cylinder 1 has a cylinder head 16 to close it at its outer end, and a port 17, open in its bore at its outer end. The port 17 of the cylinder 1 and the port 20 of the stationary barrel 13 are interconnected through a pipe 21. A gear toothing 28, solid and coaxial with said rotative barrel 8, and a tangential rack 29 in gear with said toothing 28 are means, demonstratively, for rotating said barrel 8. The rack 29 is guided within a tangential hole 30 of said stationary barrel 13.

The pump works, in principle, as shown by the diagram of FIG. 3.

The circle 0 represents a cycle of two piston strokes, corresponding, in the case of a cam with one single lift, to one turn of the cam shaft 3. In a general way, a cycle of two piston strokes is corresponding to one turn of the cam shaft 3 divided by the number of cam lifts per turn.

The distance AB represents a piston stroke, A and B being respectively the bottom and the top dead centers. In M and N the admission and the exhaust are respectively opened and closed, while inversely, they are closed in N and M. The angle a between BA and MN is the timing phase displacement in respect to the piston stroke. The orthographic projections M and N of M and N on the stroke line BA, mark the portions BM and AN of the piston stroke BA, along which the piston runs ahead and back with the same port open, so that admission and exhaust along said portions is uneffective. The effective piston stroke is thus reduced to MN' and thisgrows from zero to BA when on drops from to zero. Accordingly, the amount of fluid delivered by the pump per cycle, and therefore per unit of time, will rise from zero to maximum pump capacity, when a will drop from 90 to zero. Fluid is displaced from admission to exhaust along the effective portion of the piston stroke, M'N=c cos cc, wherein c is the full stroke of the piston.

Materi ally, the function shown by the diagram of FIG. 3 is carried out by the pump shown in FIG. 1, as follows.

The cam 4 of the pump structure, shown in FIG. 1, has one single lift. So there is one working cycle per turn of the cam shaft 3. During a turn of said cam shaft 3, the distributor 71112 connects alternatively and for one half of the turn, the chambers 9 and 10, with the port 20. So, for each half of a turn of the cam shaft 3, and therefore, for each stroke of the piston 2, the inside of the cylinder 1 is connected alternatively, with the admission 26 and the exhaust 27. As the distributor 7- 11-12 is fixed to the cam shaft 3, it lies on the stroke line BA of the diagram shown in FIG. 3 when the piston 2 is at its top dead center in B, while the line MN is that of the barrel 8 containing the center line of the port 19. When said center line of the port 19 lies on the stroke line BA, (1:0 and effective stroke and delivery will be full. When said rotative barrel 8 is turned so that the center line of the port 19 is at 90 from the former position, the piston stroke remains unaltered, but the effective stroke is zero and there will be no delivery. Between said extreme positions, delivery will be partial and equal to full delivery cos (1, wherein a is the angle between the center line of said port 19 and the position of said center line when delivery is full. Delivery is changed from no to full by simply operating the rack 29, which turns the rotative barrel 8 by about 90, in the case of cams with a single lift.

The pump can be made as a multi-cylinder unit, and,

in this case, the rotative barrel 8 will have as many ports 19 and grooves 18, as there are cylinders in the unit, and the stationary barrel 13 will have an equal number of ports 20 and connecting pipes 21. Also, as already mentioned, the cam 4 may have more than one lift. In this case the distributor will have as many parting planes 7 as there are lifts of the cam, and twice as many chambers 9 and 10 between said parting planes, closed alternately at one or the other of their ends, as shown in FIG. 4 with reference to a cam having two lifts.

I claim:

1. A variable-delivery pump with stationary cylinders, comprising at least one cylinder, a piston in said cylinder, a cam and a shaft solid with said cam, for displacing said piston along its stroke, a spring reacting between said cylinder and said piston for keeping said piston in contact with said cam, a rotating distributor fixed to said cam shaft for opening and closing suitably the suction and the exhaust respectively into and from said cylinder, a rotative barrel and ports in said rotative barrel for said suction and exhaust, said distributor turning in said rotative barrel, said rotative barrel being angularly adjustable in respect to said piston stroke, for changing the timing of said suction and exhaust in respect to said piston stroke, thus changing the pump delivery.

2. A variable-delivery pump as in claim 1 wherein said distributor comprises a diametrally parting plane fixed to said cam shaft, two semicircular transversally opposed plates fixed respectively to the ends of said parting plane, for delimiting inside said rotative barrel, two opposite distributor chambers respectively on each side of said parting plane, said distributor chambers open respectively, one towards one, and the other towards the other end of said parting plane.

3. A variable-delivery pump as in claim 2, comprising a case for said cam shaft, bearings for said cam shaft fixed to said cam shaft case, said cylinder fixed to said cam shaft case, a stationary barrel for carrying said rotative barrel, fixed to said cam shaft case, ports in said stationary barrel for admitting and exhausting fluid respectively, in and from the inside of said stationary barrel, and a port for connecting said inside of said stationary barrel to the bore of said cylinder.

4. A variable-delivery pump as in claim 3 comprising a port at the outer end of said cylinder for admission and exhaust of fluid respectively in and from said cylinder, a cylinder head for closing said cylinder at its outer end, and a pipe, for connecting said port of said cylinder with said port of said stationary barrel.

5. A variable-delivery pump as in claim 4, wherein said rotative barrel comprises a groove extending along a suitable portion of its outer circumference, a port between said groove and the inside of said rotative barrel, said groove being located between said opposite semicircular end plates of said distributor, and said port of said stationary barrel being permanently open into said groove, said rotative barrel comprising, two further circumferential grooves, one at each side of and outside the full length of said distributor, ports between each of said further grooves and the inside of said rotative barrel, said suction and exhaust ports of said stationary barrel being constantly open respectively, into said further grooves, and means for rotating said rotative barrel.

6. A variable-delivery pump as in claim 5, comprising a plurality of cylinders with pistons operated by said cam shaft, ports in said stationary barrel, for connecting the inside of said stationary barrel to each bore of said cylinders, pipes, each for connecting each of said ports of said stationary barrel respectively, with each bore of said cylinder, grooves, in said rotative barrel, separated from each other and extending along suitable portions of external circumferences of said rotative barrel, and ports, respectively one between each of said grooves and the inside of said rotative barrel.

7. A variable-delivery pump as in claim 6, wherein said cam has a plurality of lifts and said distributor has a number of diametrally parting planes equal to that of said lifts separating the inside of said rotative barrel into a number of said distributor chambers twice that of the cam lifts, said chambers closed alternately at one of their ends by said transversely opposed plates.

References Cited by the Examiner UNITED STATES PATENTS 931,535 8/1909 Wedin 103-227 1,382,336 6/1921 Behr 103227 1,440,428 1/ 1923 Wigelius 103174 1,519,205 12/1924 Kiefer 103227 2,001,336 5/1935 Vago 10337 2,006,879 7/1935 Benedek 10337 2,381,910 8/1945 Joy 103174 LAURENCE V. EFNER, Primary Examiner. 

1. A VARIABLE-DELIVERY PUMP WITH STATIONARY CYLINDERS, COMPRISING AT LEAST ONE CYLINDER, A PISTON IN SAID CYLINDER, A CAM AND A SHAFT SOLID WITH SAID CAM, FOR DISPLACING SAID PISTON ALONG ITS STROKE, A SPRING REACTING BETWEEN SAID CYLINDER AND SAID PISTON FOR KEEPING SAID PISTON IN CONTACT WITH SAID CAM, A ROTATING DISTRIBUTOR FIXED TO SAID CAM SHAFT FOR OPENING AND CLOSING SUITABLY THE SUCTION AND THE EXHAUST RESPECTIVELY INTO AND FROM SAID CYLINDER, A ROTATIVE BARREL AND PORTS IN SAID ROTATIVE BARREL FOR SAID SUCTION AND EXHAUST, SAID DISTRIBUTOR TURNING IN SAID ROTATIVE BARREL, SAID ROTATIVE BARREL BEING ANGULARLY ADJUSTABLE 